I just opened a bottle of El Toqui Syrah and it was corked. How do you know a corked wine? It's usually fairly obvious if you have any kind of experience with wines, but if you don't, you would probably think it was just a yucky wine. Sometimes you do get "just yucky wines" that aren't corked--they're just yucky.
This one gave no indication by the cork. Sometimes the cork will be cracked or there will be oozing around the cork. That doesn't necessarily mean the wine will be corked but it means beware.
What does a corked wine taste like? That's a little more difficult to explain because it depends. This one I just opened had a beautiful color but after the nice fragrance of fruit in the room, getting closer into the glass there was a fairly strong odor of mildew, or wet newspaper. But I have had wines that smell pretty funky on opening but after a few minutes of air, the funk goes away and the wine tastes fine.
This one tasted like mildew as well. This one was obvious. But other times a wine may just be really lackluster and flat. About the only way I would know if the wine was corked or just a poorly made wine is by past experience with the wine and or vintner. This is where other reviews can be helpful as well. If I had any doubt about this wine being corked, (NW) reviewed the same wine not long ago. That's always a good check on your suspicions.
Supposedly up to 15% of wines are corked. I think that is a greatly inflated figure. In over 25 years of wine tasting, I have seen only about 2-3% corked wines which is why I question the legitimacy of alternative closures but that debate is pretty well over.
At any rate, I opened another bottle of a different wine and it was marvelous. That's the wine reviewed above! So raise a glass and remember, life is too short to drink bad wine!